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From: Greg Sabino Mullane <htamfids@gmail.com>
Date: Fri, 11 Oct 2024 12:26:40 -0400
Message-ID: <CAKAnmmJsqAPNbN8GKzJURwqTNAi+vTQVe2TbvE+BY0t=4K8ARQ@mail.gmail.com>
Subject: Re: Inefficient use of index scan on 2nd column of composite index
 during concurrent activity
To: Durgamahesh Manne <maheshpostgres9@gmail.com>
Cc: PostgreSQL mailing lists <pgsql-general@postgresql.org>
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On Fri, Oct 11, 2024 at 9:28=E2=80=AFAM Durgamahesh Manne <maheshpostgres9@=
gmail.com>
wrote:

> composite key (placedon,id)
> In concurrent mode if i use id at where clause then query plan for that i=
d
> column changes
>
> How to mitigate it rather than use seperate index for id to continue
> without change in query plan (index scan) during concurrent activity
>

Why the focus on "concurrent mode"? Perhaps explain what you mean by that.

Speaking of explain, it might help if you show us the explain plans and how
they are not coming out how you want. Also the table definitions, but feel
free to not show columns unrelated to the problem.

Cheers,
Greg

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<div dir=3D"ltr"><div dir=3D"ltr">On Fri, Oct 11, 2024 at 9:28=E2=80=AFAM D=
urgamahesh Manne &lt;<a href=3D"mailto:maheshpostgres9@gmail.com">maheshpos=
tgres9@gmail.com</a>&gt; wrote:<br></div><div class=3D"gmail_quote"><blockq=
uote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1p=
x solid rgb(204,204,204);padding-left:1ex"><div dir=3D"ltr"><div class=3D"g=
mail_quote"><div dir=3D"auto"><div dir=3D"auto"><div>composite key (placedo=
n,id)=C2=A0<br></div><div>In concurrent mode if i use id at where clause th=
en query plan for that id column changes=C2=A0</div><div><br></div><div>How=
 to mitigate it rather than use seperate index for id to continue without c=
hange in query plan (index scan) during concurrent activity=C2=A0</div></di=
v></div></div></div></blockquote><div><br></div><div>Why the focus on &quot=
;concurrent mode&quot;? Perhaps explain what you mean by that.</div><div><b=
r></div><div>Speaking of explain, it might help if you show us the explain =
plans and how they are not coming out how you want. Also the table definiti=
ons, but feel free to not show columns unrelated to the problem.</div><div>=
<br></div><div>Cheers,</div><div>Greg</div><div><br></div></div></div>

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